A. Overall Mission of the Principal Research Core (PRC) The PRC builds on our prior work to address the 3 identified implementation challenges relevant to scaling up State EBP rollouts. The PRC mission will be addressed by: (1) Capitalizing on existing multidisciplinary and mixed methods research approaches (as described in the Research Methods Core);(2) Using the National Policy Research Advisory Board input to ensure maximum utilization of study findings on implementation strategies by States (see Operations Core for details);(3) Conducting 2 developmental R34 and 3 pilot studies (via the Implementation Research Policy Scholars Program in Operations Core) to advance implementation science related to multilevel, large-scale QI implementation.